清单 20 中的函数返回矢量的矢量，这是因为每个文档都可能生成零到多个映射条目，而每个映射条目都被表示为一个矢量。

The function in Listing 20 returns a vector of vectors. This is because each document could generate zero to many map entries, and each map entry is represented as a vector.

youdao

在PDF表单中，可以有图形元素，例如矢量图像、斜线和曲线。

In the PDF form, there could be graphic elements such as a vector image, an oblique line, and a curved line.

youdao

物理中，动量是矢量，它产生于,由粒子的质量与速度。

Well, in physics, momentum is a vector, and it is a product between the mass of a particle and its velocity.

youdao

Actually, the view of vectors we take nowadays is that vectors are associated with a pair of numbers which, on the rotation of axes, transform like this.

实际上,今天我们讲矢量所用的观点是,矢量是和一组坐标值相对应的,在坐标轴旋转的过程中像这样变换

耶鲁公开课 - 基础物理课程节选

This seems to work for vectors.

这在矢量运算中仍然适用

耶鲁公开课 - 基础物理课程节选

You've got to be very used to the notion of taking a vector in some oblique direction and writing it in terms of i and j.

你们应该已经很熟悉,倾斜的坐标系中矢量的概念,和用 i 和 j 来表示该矢量的方法

耶鲁公开课 - 基础物理课程节选